The present invention relates to a centrifuge with a self-emptying drum, the jacket of which has expulsion apertures that lead from a solids space and that can be closed off by means of a piston slide, with which is associated a closure chamber that has channels for supplying closure liquid and that communicates through a let-off channel in the form of an annular gap with a chamber that can accommodate all of the closure liquid and through which let-off bores with constrictions extend from the jacket of the drum, whereby the annular gap can be closed off by means of a hydraulically controlled valve body that has a valve gap.
The annular gap in known centrifuge drums of this type, i.e. that discloses in German Patent Application No. P 35 09 139.8, is positioned between the outer surface of the valve body and the inner surface, concentric thereto, of the bottom of the drum. The gap can be closed off by means of a sealing site that projects radially inwardly below the gap. The closure chamber, which is below the piston slide, can empty only as far as the inside diameter of the sealing site, and closure liquid remains in the closure chamber, exerting residual closing force on the piston slide. This residual force results, when the drum is to be completely emptied, in the piston slide returning to its closure position upon termination of the emptying process. It is, however, frequently desirable to subject the drum to a rinsing agent subsequent to emptying, with the piston slide remaining in the opening position, to rinse out residual solids.